EP-4735507-A2 - SULFONATION TREATMENT OF IMPLANTS

Abstract

Disclosed is a method for treating a polyaryletherketone (PAEK) material to improve osseointegration properties of the PAEK material. The method includes: subjecting the PAEK material to a sulfonation process comprising contacting the PAEK material with sulfuric acid at a temperature and for a time sufficient to cause sulfonation of at least a portion of aryl groups of the PAEK material; following sulfonation and prior to exposing the PAEK material to water, subjecting the PAEK material to a physical cleaning process to remove at least a portion of excess sulfuric acid from the PAEK material; and subjecting the PAEK material to a hydrothermal process comprising contacting the PAEK material with water at a temperature and for a time sufficient to cause substantial de-sulfonation of the PAEK material. The resulting PAEK material includes porous surfaces that beneficially promote osseointegration when used in an implantable device.

Inventors

• Williamson, Randall S.
• JANORKAR, AMOL V.
• NOBLES, Kadie

Assignees

• University of Mississippi Medical Center

Dates

Publication Date

20260506

Application Date

20240627

Claims (20)

1. 1. A method of treating a polyaryletherketone (PAEK) material to improve osseointegration properties of the PAEK material, the method comprising: subjecting a PAEK material to a sulfonation process comprising contacting the PAEK material with sulfuric acid at a temperature and for a time sufficient to cause sulfonation of at least a portion of aryl groups of the PAEK material; following sulfonation and prior to exposing the PAEK material to water, subj ecting the PAEK material to a physical cleaning process to remove at least a portion of excess sulfuric acid from the PAEK material; and subjecting the PAEK material to a hydrothermal process comprising contacting the PAEK material with water at a temperature and for a time sufficient to cause substantial de-sulfonation of the PAEK material.
2. 2. The method of claim 1, wherein the sulfonation process comprises contacting the PAEK material with sulfuric acid at a temperature of 55° C to 75° C and for a time of 1 to 3 minutes.
3. 3. The method of claim 1, wherein the sulfonation process further comprises sonication, optionally with stirring, while the PAEK material is exposed to the sulfuric acid.
4. 4. The method of claim 3, wherein the sulfonation process does not include stirring of the sulfuric acid.
5. 5. The method of claim 1, wherein the hydrothermal process comprises contacting the PAEK material with water at a temperature of 45° C to 80° C for a time of 1 to 5 hours.
6. 6. The method of claim 1, wherein the physical cleaning process comprises using compressed air to remove at least a portion of the excess sulfuric acid from the PAEK material.
7. 7. The method of claim 1, wherein the PAEK material comprises one or more of polyetheretherketone (PEEK), polyetherketone (PEK), polyetherketoneketone (PEKK), poly etheretherketoneketone (PEEKK), or poly etherketoneetherketoneketone (PEKEKK).
8. 8. The method of claim 7, wherein the PAEK material consists essentially of PEEK.
9. 9. The method of claim 1 , further comprising grinding a surface of the PAEK material and optionally washing the PAEK material prior to subjecting the PAEK material to the sulfonation process.
10. 10. The method of claim 9, wherein grinding the surface of the PAEK material comprises using a grit paper rated at 220 grit to 440 grit.
11. 11. The method of claim 1, wherein the sulfuric acid used in the sulfonation process has an acid concentration greater than 80% and up to 100%.
12. 12. The method of claim 1, wherein a treated surface of the PAEK material exhibits a pore coverage (% area) of 5% or greater as a result of the method.
13. 13. The method of claim 1, wherein a treated surface of the PAEK material exhibits an average pore diameter of 80 pm or greater as a result of the method.
14. 14. An implantable PAEK material manufactured using the method of claim 1.
15. 15. A method of treating a polyaryletherketone (PAEK) material to improve osseointegration properties of the PAEK material, the method comprising: subjecting a PAEK material to a sulfonation process comprising contacting the PAEK material with sulfuric acid at a temperature of 55° C to 75° C and for a time of 1 to 3 minutes to cause sulfonation of at least a portion of aryl groups of the PAEK material, wherein the sulfonation process comprises sonication, optionally with stirring, while the PAEK material is exposed to the sulfuric acid; optionally, following sulfonation and prior to exposing the PAEK material to water, subjecting the PAEK material to a physical cleaning process to remove at least a portion of excess sulfuric acid from the PAEK material; and subjecting the PAEK material to a hydrothermal process comprising contacting the PAEK material with water at a temperature of 40° C to 80° C for a time of 1 to 5 hours to cause substantial de-sulfonation of the PAEK material.
16. 16. The method of claim 15, the method comprising subjecting the PAEK material to a physical cleaning process to remove at least a portion of excess sulfuric acid from the PAEK material, wherein the physical cleaning process comprises using compressed air to remove at least a portion of the excess sulfuric acid from the PAEK material.
17. 17. The method of claim 15, wherein the PAEK material comprises one or more of polyetheretherketone (PEEK), polyetherketone (PEK), polyetherketoneketone (PEKK), poly etheretherketoneketone (PEEKK), or poly etherketoneetherketoneketone (PEKEKK).
18. 18. The method of claim 15, wherein a treated surface of the PAEK material exhibits (i) a pore coverage (% area) of 5% or greater as a result of the method and (ii) an average pore diameter of 80 pm or greater as a result of the method.
19. 19. An implantable PAEK material manufactured using the method of claim 15.
20. 20. The implantable PAEK material of claim 19, wherein the PAEK material is a spinal fusion cage.

Description

SULFONATION TREATMENT OF IMPLANTS CROSS-REFERENCE TO RELATED APPLICATIONS [0001] This application claims priority to and the benefit of United States Provisional Patent Application No. 63/523,624, filed June 27, 2023 and titled “Sulfonation Treatment of Medical and Dental Implants,” the entirety of which is incorporated herein by reference. BACKGROUND [0002] The need for orthopedic implants to treat musculoskeletal disorders has been on the rise and is expected to continue increasing as the age of the population increases. For example, the field has experienced a marked increase in spinal procedures in recent years. However, up to 10% of these implants experience failure due to causes such as poor osseointegration, infection, and failure/breakage. Similar issues persist with respect to other types of medical and dental implants intended for osseointegration. Osseointegration is the direct connection between living bone and the surface of an implant and is crucial for the long-term success of an implant. [0003] Successful osseointegration into an implant interface is mainly influenced by material stiffness and porosity. To promote osseointegration, polymer materials are subjected to surface modification. Polyetheretherketone (PEEK) is a semi-crystalline non- resorbable polymer, which is radiolucent, biocompatible, and resistant to most chemicals. PEEK has gained popularity as an alternative replacement for titanium-based implants in orthopedic applications over recent decades. PEEK has an elastic modulus of 3-8 GPa, which is similar to the 7-30 GPa range of human cortical bone, and thus the problem of stress shielding often seen with titanium implants, which have an elastic modulus of 55- 110 GPa, is diminished when using a PEEK -based material. [0004] However, one disadvantage of utilizing PEEK is that the material is bioinert and integrates poorly without surface modifications to elicit desirable cellular responses. Accordingly, there is an ongoing need for improved surface treatments that can improve the properties of PEEK and similar polymers in the context of implantable devices. SUMMARY [0005] Disclosed is a method for treating a polyaryletherketone (PAEK) material, such as PEEK, to improve osseointegration properties of the PAEK material. The method includes: subjecting the PAEK material to a sulfonation process comprising contacting the PAEK material with sulfuric acid at a temperature and for a time sufficient to cause sulfonation of at least a portion of aryl groups of the PAEK material; following sulfonation and prior to exposing the PAEK material to water, subjecting the PAEK material to a physical cleaning process to remove at least a portion of excess sulfuric acid from the PAEK material; and subjecting the PAEK material to a hydrothermal process comprising contacting the PAEK material with water at a temperature and for a time sufficient to cause substantial de-sulfonation of the PAEK material. [0006] The resulting PAEK material includes porous surfaces that beneficially promote osseointegration when used in an implantable device. The implantable device can take any form where the intent is for the implant to undergo osseointegration following placement in a subject. Suitable implantable devices include, for example, spinal implants (e.g., spinal fusion cages / intervertebral spacers, spinal rods), orthopedic implants (e.g., joint replacement components, bone screws, plates, pins), dental implants (e.g., temporary abutments, healing caps, implant fixtures), and cranial/maxillofacial implants (e.g., skull plates, skull patches, maxillofacial implants). [0007] The sulfonation process can include sonication, optionally with stirring, while the PAEK material is exposed to the sulfuric acid. The method can include a preliminary step of grinding a surface of the PAEK material and optionally washing the PAEK material prior to subjecting the PAEK material to the sulfonation process. The physical cleaning process can include using compressed air to remove at least a portion of the excess sulfuric acid from the PAEK material. [0008] In one embodiment, the method comprises subjecting a PAEK material to a sulfonation process comprising contacting the PAEK material with sulfuric acid at a temperature of 55° C to 75° C and for a time of 1 to 3 minutes to cause sulfonation of at least a portion of aryl groups of the PAEK material; following sulfonation and prior to exposing the PAEK material to water, subjecting the PAEK material to a physical cleaning process to remove at least a portion of excess sulfuric acid from the PAEK material; and subjecting the PAEK material to a hydrothermal process comprising contacting the PAEK material with water at a temperature of 40° C to 80° C for a time of 1 to 5 hours to cause substantial de-sulfonation of the PAEK material. [0009] This summary is provided to introduce a selection of concepts in a simplified form that are further described below in the detailed descript